Effect of Change of Position on the Function of the Canine Lower Esophageal Sphincter

This study was done to determine the influence of intrathoracic displacement on the function of the lower esophageal sphincter (LES), and to determine how gastroesophageal competence is restored by operations that replace the LES below the diaphragm. LES function was studied manometrically and cinefluorographically in 23 dogs, under resting conditions and during abdominal compression. Vagotomy at the canine gastroesophageal junction resulted in a decrease in resting intraluminal pressure at the LES, and in the pressure response of the LES to abdominal compression. When the vagotomized LES was displaced into the chest, pressures decreased further, and the LES became incompetent. Replacement of the vagotomized LES below the diaphragm improved resting LES pressure but did not restore competence in all animals. Fundic-wrap combined with abdominal replacement of the LES was most effective in restoring competence, and this was associated with increases both in resting LES pressure and in the response to compression. Recovery of the LES response to compression was associated with downward displacement of the LES into the abdomen and elongation of the high pressure zone.